Disclosed is a fluid dispenser, integrated into one hand piece (1). The fluid dispenser comprises a variable volume chamber, a plunger (8), a power source (5), a motor (3), a trigger (2) and a controller (6). The plunger translates in a linear direction relative to the chamber along a common longitudinal axis. The plunger acts to draw a volume of fluid into the chamber via a chamber inlet (13) and/or expel the fluid from the chamber via a chamber outlet (14). The power source and motor drive the translational movement of the plunger thereby causing a change in the volume of the chamber resulting in drawing or expelling fluid into or from the chamber. The trigger, when activated causes fluid to be expelled from the chamber. The controller is operatively linked to the plunger and chamber, wherein the controller acts to control the volume expelled and/or drawn into the chamber by varying plunger translation distance, direction and/or speed. The volume of fluid drawn or expelled into or from the chamber is based on the weight of the subject to be dosed.
